"... The authors present a unified account of 2 neural systems concerned with the development and expression of adaptive behaviors: a mesencephalic dopamine system for reinforcement learning and a “generic ” error-processing system associated with the anterior cingulate cortex. The existence of the error ..."

The authors present a unified account of 2 neural systems concerned with the development and expression of adaptive behaviors: a mesencephalic dopamine system for reinforcement learning and a “generic ” error-processing system associated with the anterior cingulate cortex. The existence of the error-processing system has been inferred from the error-related negativity (ERN), a component of the event-related brain potential elicited when human participants commit errors in reaction-time tasks. The authors propose that the ERN is generated when a negative reinforcement learning signal is conveyed to the anterior cingulate cortex via the mesencephalic dopamine system and that this signal is used by the anterior cingulate cortex to modify performance on the task at hand. They provide support for this proposal using both computational modeling and psychophysiological experimentation. Human beings learn from the consequences of their actions. Thorndike (1911/1970) originally described this phenomenon with his law of effect, which made explicit the commonsense notion that actions that are followed by feelings of satisfaction are more likely to be generated again in the future, whereas actions that are followed by negative outcomes are less likely to reoccur. This

...ividuals with prefrontal damage make repeated errors when performing certain psychological tasks, they can still verbally report when their responses are correct and incorrect (Konow & Pribram, 1970; =-=Milner, 1963-=-; Picton, Stuss, & Marshall, 1986; but see Slachevsky et al., 2001). This observation has motivated the proposition that the prefrontal cortex, although not involved in error detection, is concerned w...

"... this paper. The cortex on the orbital surface of the frontal lobe includes area 13 caudally and area 14 medially, and the cortex on the inferior convexity includes area 12 caudally and area 11 anteriorly (Fig. 1) (Carmichael and Price, 1994; Petrides and Pandya, 1994; Price et al., 1996). This br ..."

this paper. The cortex on the orbital surface of the frontal lobe includes area 13 caudally and area 14 medially, and the cortex on the inferior convexity includes area 12 caudally and area 11 anteriorly (Fig. 1) (Carmichael and Price, 1994; Petrides and Pandya, 1994; Price et al., 1996). This brain region is well developed in primates, including humans, but poorly developed in rodents, with homologies to areas found in primates uncertain, so that care must be used in interpretation of the term `orbitofrontal &apos; when applied to rodents (Uylings and van Eden, 1990). To understand the function of this brain region in humans, the majority of the studies described were therefore performed with macaques or with humans

"... Practice of a novel task leads to improved performance. The brain mechanisms associated with practice-induced improvement in performance are largely unknown. To address this question we have examined the functional anatomy of the human brain with positron emission tomography (PET) during the naive a ..."

Practice of a novel task leads to improved performance. The brain mechanisms associated with practice-induced improvement in performance are largely unknown. To address this question we have examined the functional anatomy of the human brain with positron emission tomography (PET) during the naive and practiced per-formance of a simple verbal response selection task (saying an appropriate verb for a visually presented noun). As a control state, subjects were asked to repeat the visually presented nouns. Areas of the brain most active during naive performance (anterior cingulate, left prefrontal and left posterior temporal cortices, and the right cerebellar hemisphere), compared to repeating the visually presented nouns, were all significantly less ac-tive during practiced performance. These changes were

"... ABSTRACT An Important aspect of cognitive control is the ability to appropriately select, update, and maintain contextual information related to behavioral goals, and to me this information to coordinate processing over extended periods. In our novel, neurobiologicaUy based, connectionist computatio ..."

ABSTRACT An Important aspect of cognitive control is the ability to appropriately select, update, and maintain contextual information related to behavioral goals, and to me this information to coordinate processing over extended periods. In our novel, neurobiologicaUy based, connectionist computational model, the selection, updating, and maintenance of context occur through Interactions between the prefrontal cortex @&apos;PC) and dofamlne (DA) neuiotiuismitter system. Phasic DAactivity serves two simultaneous and synergistic functions: (1) a gating function, which regulates the access of information to active memory mechanisms subserved by PFC; and (2) a learning function, whlcn auowa me system to discover wast uifonnation is relevant for selection as context. We present a simulation that establishes the computational viability of these postulated neurobiological mechanisms for subserving control functions. The need for a control mechanism in cognition has been long noted within psychology. Virtually all theorists agree that some mechanism is needed to guide, coordinate, and update behavior in a flexible fashionparticularly in novel or complex tasks (Norman and Shallice 1986). In

"... The authors examined the question of whether a decrease in the efficiency of inhibitory processing with aging is a general phenomenon. Thirty elderly and 32 young adults performed a series of tasks from which the authors could extract measures of inhibitory function. The tasks and task components in ..."

The authors examined the question of whether a decrease in the efficiency of inhibitory processing with aging is a general phenomenon. Thirty elderly and 32 young adults performed a series of tasks from which the authors could extract measures of inhibitory function. The tasks and task components included response compatibility, negative priming, stopping, spatial precuing, Wisconsin Card Sorting Test (WCST), and the Cognitive Failures Questionnaire (CFQ). Only limited evidence for age-related differences in inhibitory function was obtained. Old adults had more difficulty than young adults in stopping an overt response and adopting new rules in a categorization task. However, elderly and young adults produced equivalent negative priming effects, response compatibility effects, spatial precuing effects, and self-reported cognitive failures. The findings are discussed in terms of the relationship between aging, inhibitory processes, and neuroanatomical and physiological function. A dominant view in the aging literature is that cognitive decline in later life is the result of a progressive and generalized slowing of information-processing activities (Birren, 1974; Cerella, 1990; Salthouse, 1992). Much of the evidence for such a

...mance on the Wisconsin Card Sorting Test (WCST), particularly measures of perseverative errors, has been found to be associated with frontal lobe lesions in human patients (Drewe, 1974; Heaton, 1981; =-=Milner, 1963-=-). It is assumed that an important processing component in this task is the ability to inhibit old rules when attempting to learn new rules for the categorization of multiattribute stimuli. Thus, larg...

"... A fundamental problem that organisms face in a changing environment is how to regulate dynamically the balance between stable maintenance and flexible switching of goals and cognitive sets. The authors show that positive affect plays an important role in the regulation of this stability–flexibility ..."

A fundamental problem that organisms face in a changing environment is how to regulate dynamically the balance between stable maintenance and flexible switching of goals and cognitive sets. The authors show that positive affect plays an important role in the regulation of this stability–flexibility balance. In a cognitive set-switching paradigm, the induction of mild increases in positive affect, as compared with neutral or negative affect, promoted cognitive flexibility and reduced perseveration, but also incurred a cost in terms of increased distractibility. Rather than influencing set switching in an unspecific way, positive affect thus exerted opposite effects on perseveration and distractibility. Results are consistent with neuropsychological models according to which effects of positive affect on cognitive control are mediated by increased dopamine levels in frontal brain areas. Intelligent organisms pursuing goal-directed behavior in a con-stantly changing environment face two fundamental challenges: to maintain current goals over time in the face of distraction on the one hand, and to flexibly switch between goals and update working memory in response to significant changes on the other (Goschke, 1996, 2000, 2003; cf. Mayr &amp; Keele, 2000; O’Reilly, Braver, &amp;

... patients often exhibit perseverative behavior and reduced cognitive flexibility in tasks that require switching between different categorization rules, such as the Wisconsin Card Sorting Test (WCST; =-=Milner, 1963-=-; Nelson, 1976). On the other hand, prefrontal patients suffer from increased distractibility and stimulus-driven behavior. For instance, some patients show “utilization behavior,” that is, they appea...

"... Ninety-two mixed etiology neurological patients and 216 control participants were assessed on a range of neuropsychological tests, including 10 neuropsychological measures of executive function derived from 6 different tests. People who knew the patients well (relatives or carers) completed a questi ..."

Ninety-two mixed etiology neurological patients and 216 control participants were assessed on a range of neuropsychological tests, including 10 neuropsychological measures of executive function derived from 6 different tests. People who knew the patients well (relatives or carers) completed a questionnaire about the patient’s dysexecutive problems in everyday life, and this paper reports the extent to which the tests predicted the patients’ everyday life problems. All of the tests were significantly predictive of at least some of the behavioral and cognitive deficits reported by patients ’ carers. However, factor analysis of the patients ’ dysexecutive symptoms suggested a fractionation of the dysexecutive syndrome, with neuropsychological tests loading differentially on 3 underlying cognitive factors (Inhibition, Intentionality, and Executive Memory), supporting the conclusions that different tests measure different cognitive processes, and that there may be limits to the fractionation of the executive system. (JINS, 1998, 4, 547–558.)

...tate of some brain process(es) that are presumed to be utilized in situations outside the strict test situation; after all, an isolated impairment in performing the Wisconsin Card Sorting Test (WCST; =-=Milner, 1963-=-), with no other problems in any other situation, would be of little clinical significance. Instead, failure on, for instance, the WCST is normally taken as suggesting that the cognitive processes inv...

"... Whether frontal obe pathology can account for some of the cognitive impairment observed in amnesic patients with Korsakoff's yndrome was investigated. Various cognitive and memory tests were given to patients with circumscribed frontal obe lesions, patients with KorsakotVs syndrome, non-Korsako ..."

Whether frontal obe pathology can account for some of the cognitive impairment observed in amnesic patients with Korsakoff&apos;s yndrome was investigated. Various cognitive and memory tests were given to patients with circumscribed frontal obe lesions, patients with KorsakotVs syndrome, non-Korsakoff amnesic patients, and control Ss. Patients with frontal obe lesions were not amnesic. Nevertheless, they exhibited 2deficits that were also exhibited by patients with Korsakoff&apos;s yndrome but not by other amnesic patients: (a) impairment on the Wisconsin Card Sorting Test and (b) impairment on the Initiation and Perseveration subscale of the Dementia Rating Scale. Thus, frontal obe pathology can explain some of the cognitive deficits observed in patients with Korsakotrs yndrome. Amnesia is characterized by a severe deficit in the ability to learn new facts and events (i.e., anterograde amnesia) in the context of relatively preserved intellectual functions (for reviews see Cermak, 1982; Hirst, 1982; May es &amp; Meudell,